Vector monitor

Vector displays do not suffer from the display artifacts of aliasing and pixelation—especially black and white displays; color displays keep some artifacts due to their discrete nature—but they are limited to displaying only a shape's outline (although advanced vector systems can provide a limited amount of shading). Text is crudely drawn from short strokes. Refresh vector displays are limited in how many lines or how much text can be shown without refresh flicker. Irregular beam motion is slower than steady beam motion of raster displays. Beam deflections are typically driven by magnetic coils, and those coils resist rapid changes to their current.

History

The vector display was first invented by Jonathan Zenneck via use of a Braun cathode-ray tube. His solution was able to produce fundamental waveforms using two deflection cowls a high-powered cathode inside of the tube to create a continuously swept image.^[1] This device was utilized by early radio engineers, but was not practical until John Bertrand Johnson implemented the hot cathode to drastically reduce the voltage requirements for the device. The Cathode Ray Oscillograph was subsequently commercialized and became the basis for the modern oscilloscope.^[2]

Oscilloscopes were used by electrical engineers to map out physical forces, as well as by recording engineers to understand the nature of human voices.^[3] The displays also became a frequent add-on to advanced electronic analog computers to visualize complex forces. The first RADAR systems utilized vector graphic oscilloscopes to map aircraft positions.

Vector graphics in computers first emerged with the

In 1963, Ivan Sutherland at MIT first used a vector graphic display for Sketchpad, his pioneering CAD program. In 1968, he and his team again used a vector monitor to display wireframe images of 3D models. This time the display was head mounted. The obviously heavy system was held up by a support arm structure called The Sword of Damocles. The system is widely considered to be the first computer-based virtual reality.

In 1970, at the UK Farnborough Airshow, Sperry Gyroscope (Bracknell, England) exhibited the first ever vector graphic video display from a UK company. It featured an analogue monochrome display with special electronics, designed by Sperry's John Atkins, that allowed it to draw vectors on screen between two pairs of coordinates. At Farnborough the display was used to demonstrate the capabilities of the new Sperry 1412 military computer - it was shown running software that drew, in real time, a wire-frame rotating cube that could be speed-controlled in any of its three dimensions. That demonstration created significant interest in the Sperry 1412 computer, which then went on to be at the heart of a number of major projects for the French Navy and the Royal Navy during the period 1972 to 1992.

Examples

Notable among vector displays are Tektronix large-screen computer terminals that use direct-view storage CRTs. (The CRT has at least one

Vector displays were used for head-up displays in fighter aircraft because of the brighter displays that can be achieved by moving the electron beam more slowly across the phosphors. Brightness was critical because the display needed to be clearly visible to the pilot in direct sunlight.

Vector monitors were also used by some late-1970s to mid-1980s arcade games such as

Hewlett-Packard made a series of large-screen X-Y (vector) displays, the first of which was the 20 MHz 8x10-inch model 1300. The CRT had an internal, specially contoured, very fine mesh operating at low potential, which was placed after the deflection plates at the gun exit. The 17KV electrostatic field between this mesh and the separate, conductive coating charged to final accelerating potential inside the CRT funnel, accelerated the electron beam axially as well as radially, expanding the possible image size to cover the 8x10" screen of the 17.75-inch long CRT. Without the mesh, the 8x10-inch CRT would have had to be almost three times as long.^[6] Expansion mesh technology was developed in the early 1960s^[7] by the need to drive deflection plates at high frequencies in compact high-brightness CRTs operating at high acceleration voltages, to take advantage of the then-new transistor technology which was limited to only low voltages. The much bulkier and less efficient vacuum-tube electrostatic deflection amplifiers were able to operate at hundreds of volts.

Color displays

Some vector monitors are capable of displaying multiple colors, using either a typical shadow mask RGB CRT or two phosphor layers (so-called "penetration color").

Atari used the term color quadrascan to describe the shadow-mask version used in their video arcade games.^[8][9]

In the penetration tubes, by controlling the strength of the electron beam, electrons can be made to reach (and illuminate) either or both phosphor layers, typically producing a choice of green, orange, or red.

Tektronix made color oscilloscopes for a few years using penetration CRTs, but demand for these was low.^{[citation needed]}

Some monochrome vector displays were able to display color using peripherals such as the Vectrex 3-D Imager.

See also

• Vector graphics
• Vectrex
• Raster scan

References